Low Band Gap Benzoxazole‐Linked Covalent Organic Frameworks for Photo‐Enhanced Targeted Uranium Recovery

• Published in: Small (Weinheim an der Bergstrasse, Germany) Vol. 17; no. 6; pp. e2006882 - n/a
• Main Authors: Cui, Wei‐Rong, Zhang, Cheng‐Rong, Xu, Rui‐Han, Chen, Xiao‐Rong, Yan, Run‐Han, Jiang, Wei, Liang, Ru‐Ping, Qiu, Jian‐Ding
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01.02.2021
• Subjects: Chemical reduction; covalent organic frameworks; Energy gap; Hydrophilicity; Hydroxyl groups; Nanotechnology; photocatalytic; photothermal; Recovery; Seawater; Selectivity; Synergistic effect; Uranium; uranium recovery; photothermal; covalent organic frameworks; photocatalytic; chemical reduction; uranium recovery
• ISSN: 1613-6810; 1613-6829; 1613-6829
• DOI: 10.1002/smll.202006882

The inherent features of covalent organic frameworks (COFs) make them highly attractive for uranium recovery applications. A key aspect yet to be explored is how to improve the selectivity and efficiency of COFs for recovering uranium from seawater. To achieve this goal, a series of robust and hydrophilic benzoxazole‐based COFs is developed (denoted as Tp‐DBD, Bd‐DBD, and Hb‐DBD) as efficient adsorbents for photo‐enhanced targeted uranium recovery. Benefiting from the hydroxyl groups and the formation of benzoxazole rings, the hydrophilic Tp‐DBD shows outstanding stability and chemical reduction properties. Meanwhile, the synergistic effect of the hydroxyl groups and the benzoxazole rings in the π‐conjugated frameworks significantly decrease the optical band gap, and improve the affinity and capacity to uranium recovery. In seawater, the adsorption capacity of uranium is 19.2× that of vanadium, a main interfering metal in uranium extraction. Excellent photocatalytic activity, photothermal and photoelectric effects make Tp‐DBD produce biotoxic ROS, have good anti‐biofouling activity, and increase the adsorption rate and affinity of uranium binding sites, thereby improving the recovery capacity of uranium.